Non-Exercise Estimated Cardiorespiratory Fitness Mediates the Relationship Between Comorbidities and Health-Related Quality of Life in Korean Older Adults

Abstract

PURPOSE: To investigate whether or not CRF mediates the relationship of comorbidities with health-related quality of life (HRQoL) in a representative sample of Korean older adults. METHODS: Data from a total of 7,350 Korean older adults aged ≥60 years (58% women) who participated in the 2008-2011 Korean National Health and Nutritional Examination Survey were used in this analysis. HRQoL was assessed with the EuroQoL-5 dimensions (EQ-5D) index and EuroQoL visual analogue scale (EQ-VAS). Comorbidity was defined as physician-diagnosed chronic conditions. CRF was estimated with a non-exercise regression equation derived from sex, age, body mass index, and self-reported physical activity. The SPSS macro provided by Preacher and Hayes was used to test whether CRF mediated the relationship between comorbidity and HRQoL at statistical significance of p=0.05. RESULTS: The total effect of the presence of comorbidities on HRQoL was significant (path c; β=-3.091, p<0.001). The presence of comorbidities was negatively related to eCRF in HRQoL model (path a: β=-0.403, p<0.001). As illustrated in Fig.1, the effect of eCRF as a mediator on HRQoL was also significant (path b: β=1.574, p<0.001). The mediation analysis using the bootstrapping method (5,000 resamples) showed that eCRF mediated the relationship between the presence of comorbidities and HRQoL in Korean older adults (path a × b: β=-0.635, 95% CI=-0.746 ~ -0.524, Sobel test result Z=-11.029, p<.001). In addition, a direct effect of the presence of comorbidities on HRQoL was also significant (path c’: β=-2.456, p<0.001). CONCLUSIONS: The current findings suggest that CRF mediates the relationship between comorbidities and HRQoL in Korean older adults. Supported by the National Research Foundation funded by the Korean Government (NRF-2018R1D1A1B07048153 and NRF-2016R1A6A3A11932432).Fig. 1: The estimation of the direct and indirect effect of eCRF on health related quality of life.